RSA private keys can be recovered if you know the two Primes (technically only one is needed) that were used for generation.
You need to know P and Q seeds (At least one of them really) to begin the recovery process.
To use: Open the file and paste in your seeds in the P and Q variables and python2 run it.
python2 ./decryptRSA.py
Additional: This can be easily converted into use in python 3 by changing long casts to int.